feat: Deprecated Function Checker

[notJoon]

Description

Add a deprecated functon checker that identifies the usage and suggests a alternative functions if possible.

Implementation Details

The core of this implementation is the DeprecatedFuncChecker struct type, which maintains a map of deprecated functions along with their alternative functions.

How Deprecated Functions are Recognized

1. Registration: Deprecated functions are registered using thr Register method, which takes three parameters
   • Package name
   • Function name
   • Alternative function (packageName.funcName format)
2. Function Call Identification: For each AST node, the checker looks for *ast.CallExpr nodes, which represent function calls.
3. Selector Expression Analysis: It then checks if the function call is a selector expression (*ast.SelectorExpr), which is typical for package.Function() calls.
4. Package and Function Matching: The checker extracts the package name and function name from the selector expression and compares them against the registered deprecated functions.

Usage Example

checker := NewDeprecatedFuncChecker()
checker.Register("fmt", "Println", "fmt.Print")
checker.Register("os", "Remove", "os.RemoveAll")

deprecated, err := checker.Check(filename, astNode, fileSet)
if err != nil {
    // Handle error
}

for _, dep := range deprecated {
    fmt.Printf("Deprecated function %s.%s used. Consider using %s instead.\n",
        dep.Package, dep.Function, dep.Alternative)
}